Improvement in bit-stocks



O. PEOK. Bit-Stock.

Patented Sept. 23, I879.

UNITED STATES PATENT OFFICE BED PECK, OF ROWE, MASSACHUSETTS.

lM PROVEM ENT IN BIT-STOCKS.

Specification forming part of Letters Patent No. 219,872, datedSeptember 23, 1879; application filed January 2, 1879.

1'0 all whom it may concern:

Be it known that I, OBED PEGK, of Rowe, in the county of Franklin andState of Massachusett-s, have made certain new and useful Improvementsin Bit-Stocks, whereof the following is a specification, reference beinghad to the accompanying drawings, in which-- Figure 1 represents alongitudinal section of my brace, taken through the line .90 m of Fig.2. Fig. 2 is a frontend view of my bitbrace. Fig. 3 shows the jaw piecewhich draws the bit-shank into the socket and holds. it there. Fig. 4shows the head of my bitbrace attached to the sweep, with the jaw-pieceand thumb-nut removed.

A is a shell, solidly attached to and forming part of the common sweep Dof a bit-brace, which, being well known, is'not fully represented. Saidshell -has in its upper end a socket, E, to hold the shanks of bits.Through "the shell A, into its socket E, is out a slot, F,

large enough to admit the jaw-piece B, and in which the jaw-piece hasbearings c f; and through the opposite side of shell A is made a hole,through which the end tOf the jawpiece passes, and in which it has thebearings g h.

C is a threaded thumb-nut, operating on the thread 01 of the jaw-pieceB. The jaw-piece B, which I usually make of steel and temper like acold-chisel, has a chisel-shaped edge, 12, one side of which is formedof the incline a, tending downward into the socket when in place.

The line 0 represents the axis of rotation of a bit and its shank in thesocket in operation.

The bearings e f g h are located at obtuse angles, as shown, to saidaxis of rotation, so that any part taking hold of the bit-shank andforced along said hearings, or either of them, would be by them driveninward from the outer end of the brace-head, and would draw the shankinward into socket E.

The operation of the brace is as follows: The thumb-nut U is loosenedsufliciently to allow the edge b to be pushed out of the socket E, and abit is introduced, the shank entering said socket. Then the thumb-nutOis turned,

drawing, by its screw purchase, the edge b with great force against someportion, preferably the corner, of the bit-shank, and, as the jaw-piecemoves along the bearings'e f g h, forcing the shank downward into thesocket E, and firmly holding it there. The edge-b cuts into the shank,cutting its notch therein, and thereby taking hold of the same tooperate upon it.

Two parts of the mechanism combine to draw the shank inward into thesocket E. First, the inclined surface (t bears against the shank of thebit as it is driven into it, and tends to drive the edge b forward byits inclination, thereby drawing inward the shank, and also making anotch in it of suitable shape to draw inward the shank at-its nextinsertion, and this advantage is gained more or less in proportion asthe angle of the bevel with the line of motion of an entering shank onthe side a of the edge b is less than on the other side; second, theline of draft of the thumb-nut is inward, because the bearings e f g hhave the inclinations described, thereby guiding the jaw-piece downwardafter it takes hold of the shank, and drawingthe, shank with it firmlyinto its hearings in the socket.

I have preferred to draw the" edge 0 into the shank by a jaw-pieceprojecting through the opposite side of the head, because its point 0'projects into position to be conveniently struck a light blow if thejaw-piece sticks when the nut is loosened, and because of additionalleverage procured by its shape, and for other reasons.

Obviously the edge b might be driven into the shank by a thumb-screwapplied on the side of the jaw-piece opposite the thumb-nut 0, near thebearing 6, when that hearing would, from its inclination, force the edgedownward and draw the shank inward into the socket, an essential part ofthe invention being the jaw-piece taking hold of the shank and drivenalong a hearing which guides it, and the shank with it, downward intothe socket.

J aw-pieces have been made with a threaded end extending lengthwisethrough the head and a part of the sweep, so as to draw inward directlythe shank when applied to it. In these constructions the nut is in the.way of the hand when operating the brace, and they are expensive.

My invention has for a principal purpose to obviate this difliculty, anddraw the shank down into the socket, while the thumb-nut is located inthe convenient place at the side of the brace-head.

Obviously any handle may be applied to part A in place of the sweep D.

What I claim, and for which I pray Letters Patent, is-- 1. The jaw-pieceB and nut 0, combined with the shell A, having a socket to receive andhold bit-shanks, when said jaw-piece has a chisel-edge, b, of which thebevel on the side of said edge in the direction toward which a bit-shankmoves in entering said socket makes a greater angle with the line ofmotion of said shank in entering the same than the bevel on the otherside of said edge.

2. The jaw-piece B, having one or more bearings in the shell A, inclinedas described, to guide it inward from the outer end of said shell, forthe purposes described.

OBED PEGK.

In presence of- DANIEL POWERS, W. R. BUZZELL.

